Run-time evaluation of opportunities for object inlining

Object-oriented languages, like Java, encourage the use of many small objects linked together by eld references, instead of a few monolithic structures. While this practice is benecial from a program design perspective, it can slow down program execution by incurring many pointer indirections. One solution to this problem is object inlining: when the compiler can safely do so, it fuses small objects together, thus removing the reads/writes to the removed eld, saving the memory needed to store the eld and object header, and reducing the number of object allocations. The objective of this paper is to measure the potential for object inlining by studying the run-time behavior of a comprehensive set of Java programs. We study the traces of program executions in order to determine which elds behave like inlinable elds. Since we are using dynamic information instead of a static analysis, our results give an upper bound on what could be achieved via a static compiler-based approach. Our experimental results measure the potential improvements attainable with object inlining, including reductions in the numbers of eld reads and writes, and reduced memory usage. Our study shows that some Java programs can benet signicantly from object inlining, with close to a 10 % speedup. Somewhat to our surprise, our study found one case, the db benchmark, where the mos